Hello MadAlice,
If this is happening in the PTR, please keep in mind we can’t really offer technical support for the test servers. Due to their nature, it’s possible to experience bug or technical issues while playing there.
I’d recommend starting by checking this message on the forum, and following all the instructions:
This message is a compilation of the most common causes for this kind of error. Unfortunately, this error can be tricky to diagnose in the forums, since it can often be related to hardware or power issues.
If nothing helps, my recommendation would be taking your PC to a local technician so they can make sure everything is working as it should.
Got feedback about the support I’m providing? Leave your comments here!